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Rule 35: status, sequence and intervals

Underway, anchored and aground do not share one pattern; below twelve metres does not mean silence.

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In this guide
Base35 patterns:a one prolonged,b two,c one+two shorts,e one+three shorts when manned; repetition≤2min. g bell≈5s/≤1min;h3strokes+rapid bell+3strokes. i/j efficient alternatives≤2min and k4optional additional shorts. Full conditions/additions in text; no audio or interval scale.
Rule 35 · status and pattern

Original interpretation schematic with declared functions and references. No scale, approved installation or operational track.

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Base35 patterns:a one prolonged,b two,c one+two shorts,e one+three shorts when manned; repetition≤2min. g bell≈5s/≤1min;h3strokes+rapid bell+3strokes. i/j efficient alternatives≤2min and k4optional additional shorts. Full conditions/additions in text; no audio or interval scale.

Rule 35 prescribes signals in or near restricted visibility by day and night. It does not require the other vessel to be invisible: a vessel can remain in sight near the area.

It distinguishes status, way through the water, activity, manning and length. Maximum repetition interval is not blast duration.

The figure identifies sequences and repetition limits without audio or a usable appliance. Look-out and collision-prevention obligations remain.

Underway and through the water

Under 35(a), machinery making way gives one prolonged at intervals no greater than two minutes. Under (b), underway but stopped and making no way through the water gives two prolongeds about two seconds apart, repeated at no more than two minutes.

Short and prolonged retain Rule 32 durations. Ground speed cannot decide alone: current can transport a hull without way through the water or cancel its progress through the water.

Paragraph (c) groups not under command, restricted manoeuvrability, constrained draught, sail, fishing and towing/pushing: one prolonged followed by two shorts, at intervals no greater than two minutes instead of (a)/(b). Under (d), fishing at anchor and restricted-manoeuvrability work carried out at anchor use (c) instead of (g)’s bell.

Not every anchored vessel uses only the same signal, and not every vessel with a mast is sailing.

The tow, or last tow in a group, when manned, uses under (e) one prolonged and three shorts with a two-minute limit, immediately after the towing vessel where practicable. Manning must not disappear from the condition.

A rigid composite pushing unit is treated by (f) as power-driven, returning to (a)/(b). A rope connection does not establish that status.

Activity and connection type explain why similar views can require different patterns.

Anchoring, grounding and dimensions

Under (g), anchoring uses rapid bell ringing for about five seconds at intervals no greater than one minute; from one hundred metres, forward, followed by about five seconds of gong aft. Short-prolonged-short may additionally warn an approaching vessel of position and collision possibility.

Under (h), grounding adds three separate distinct bell strokes immediately before and after rapid ringing, with gong where required. An appropriate whistle signal may be added.

An optional sound does not automatically replace the required one.

From twelve metres inclusive to twenty exclusive, (i) exempts (g)/(h)’s bell patterns; if not given, another efficient sound signal is required at no greater than two-minute intervals. Below twelve, (j) exempts the preceding sequences but likewise requires an efficient signal at that limit if they are not given.

It does not authorise silence. On pilotage duty, (k) permits four identity shorts in addition to the applicable (a), (b) or (g).

The Inland special-anchorage exception is not imported.

Current consultation confirmed (j) and (k) in normative Portuguese IH 2025 and USCG International, including its current page. The IH English appendix omits under-twelve (j) and calls the pilot paragraph (j); that editorial difference is recorded without altering the historical reference.

This lesson follows the stated normative agreement with exact locators. Documentary cross-checking is not legal approval or a training certificate.

Sources and references

  1. RIEAM / COLREGs — Rule 19: Conduct of vessels in restricted visibility ↗

    Instituto Hidrográfico / International Maritime Organization · Rule 19, normative Portuguese printed p.26 (PDF p.32); International English cross-check in USCG handbook.

    Rule 19; IH normative Portuguese printed p.26, PDF p.32; English International column cross-check. Individual provision commencement not established: valid_from remains null.

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  2. USCG amalgamated rules — International current web cross-check ↗

    United States Coast Guard Navigation Center · International/shared Rules 3,20–30,32–35; International Annexes I–III. International-only wording identified by angle-bracket legend; all Inland insertions excluded. Rule35(j)/(k) compared with IH normative Portuguese printed55/PDF61 and English appendix89–90/PDF95–96.

    Directly read 11 October2026 alongside freshly fetched corrected-August2024 official handbook. Current page confirms under12 paragraph(j) and pilot(k); Portuguese IH agrees; its English appendix differs. Access is not qualified legal approval. No unsupported exact consolidation date assigned.

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  3. RIEAM / COLREGs — Rule 4: Application of Section I ↗

    Instituto Hidrográfico / International Maritime Organization · Rule 5, normative Portuguese printed p.7 (PDF p.13); International English cross-check in USCG handbook.

    Rule 5; IH normative Portuguese printed p.7, PDF p.13; English International column cross-check. Individual provision commencement not established: valid_from remains null.

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  4. RIEAM / COLREGs — Rule 35: Sound signals in restricted visibility ↗

    Instituto Hidrográfico / International Maritime Organization · Rule 35, normative Portuguese printed p.55 (PDF p.61); International English cross-check in USCG handbook.

    Rule 35; IH normative Portuguese printed p.55, PDF p.61; English International column cross-check. Individual provision commencement not established: valid_from remains null. Review discrepancy: IH English appendix printed pp.89–90 omits current paragraph (j), the under-12m alternative, and labels pilot clause (j). USCG International Rule35(j)/(k) supplies the current distinction; Editorial source concordance checked 2026-10-11: IH Portuguese normative Rule35(j)/(k), PDF61, and USCG INTERNATIONAL Rule35(j)/(k), PDF113, agree. The IH English appendix omission/misnumbering remains recorded; no professional approval is claimed.

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  5. RIEAM / COLREGs — Rule 2: Responsibility ↗

    Instituto Hidrográfico / International Maritime Organization · Rule 3, normative Portuguese printed p.3 (PDF p.9); International English cross-check in USCG handbook.

    Rule 3; IH normative Portuguese printed p.3, PDF p.9; English International column cross-check. Individual provision commencement not established: valid_from remains null.

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  6. RIEAM / COLREGs — Rule 32: Definitions of sound signals ↗

    Instituto Hidrográfico / International Maritime Organization · Rule 32, normative Portuguese printed p.53 (PDF p.59); International English cross-check in USCG handbook. Rule 33, normative Portuguese printed p.53 (PDF p.59); International English cross-check in USCG handbook.

    Rule 32; IH normative Portuguese printed p.53, PDF p.59; English International column cross-check. Individual provision commencement not established: valid_from remains null. Rule 33; IH normative Portuguese printed p.53, PDF p.59; English International column cross-check. Individual provision commencement not established: valid_from remains null.

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  7. COLREGs Annex III — Technical details of sound signal appliances ↗

    Instituto Hidrográfico / International Maritime Organization · Annex III; printed p.77, PDF p.83; International cross-check USCG.

    Annex III, IH printed p.77 (PDF p.83); cross-check International annex in USCG handbook. Installation/approval is not taught.

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